Viscoelastic studies on Tetrahymena macronuclear DNA. 1978

J B Williams, and E W Fleck, and L E Hellier, and E Uhlenhopp

We have used viscoelastometry in an attempt to understand the physical organization of genetic material in Tetrahymena nuclei. The micronucleus or germ line nucleus is diploid. It divides mitotically during vegetative growth, and five pairs of chromosomes are seen in meiosis. The macronucleus, or somatic nucleus, is approximately 45-ploid, divides amitotically, and has no visible chromosomes at any stage. Viscoelastic analysis of Tetrahymena macronuclei reveals DNA Molecules of 2-3 X 10(10) daltons accounting for much, if not all, of the macronuclear DNA. Since the average chromosome in the micronucleus contains 2.4-2.7 X 10(10) daltons of DNA, we deduce that the macronucleus of Tetrahymena contains chromosome-sized DNA molecules.

UI MeSH Term Description Entries
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
D002467 Cell Nucleus Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed) Cell Nuclei,Nuclei, Cell,Nucleus, Cell
D002875 Chromosomes In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed) Chromosome
D004247 DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004548 Elasticity Resistance and recovery from distortion of shape.
D013769 Tetrahymena pyriformis A species of ciliate protozoa used extensively in genetic research. Tetrahymena pyriformi,pyriformi, Tetrahymena
D014783 Viscosity The resistance that a gaseous or liquid system offers to flow when it is subjected to shear stress. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Viscosities

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